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Chronic Fatigue Syndrome

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At this time, there is no blood test, brain scan, or other lab test to diagnose CFS. The syndrome is diagnosed by exclusion through:

  • Documenting the patient's medical history
  • Performing a thorough medical examination
  • Conducting cognitive function tests
  • Ruling out other conditions that may be causing or exacerbating the fatigue (and/or identifying and treating those that can be treated)
  • Fulfilling the Centers for Disease Control and Prevention (CDC) criteria for the definition of CFS
  • Monitoring the patient over time to see if other underlying conditions arise

Laboratory tests can be useful to help diagnose and manage other conditions with similar symptoms and disorders that must be identified and treated before a diagnosis of CFS can be made. The CDC recommends a few general tests, bulleted in the next section.

Laboratory tests

Other tests may be ordered to follow up abnormal findings on the general tests and as warranted by the affected individual's symptoms. These additional tests are used to help identify or rule out diseases and disorders that may be causing fatigue; they are not capable of directly diagnosing CFS. These may include:

Other laboratory tests may be used in a research setting to attempt to better understand the cause and course of CFS.

Non-laboratory tests
Occasionally, an MRI (magnetic resonance imaging) scan may be ordered to help rule out multiple sclerosis as a cause of chronic fatigue. Other tests and imaging scans may be used in a research setting but are not considered clinically useful at this time.

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